Maria von Au died 17 sept Evansville Indiana

I am looking for geanology clues for my great-great grandmother Maria von Au. I have also found she could go by Amelia or Mary. She was born 5 Sep 1839 in Thalheim, Rottenburg, Germany. Married Sebastian Digel 4 June 1857 in Henderson Kentucky and died 17 Sept 1889 in Evansville, Vanderburgh, Indiana.

She had a sister by the name of Henrietta or Hermina. Any information on linkage to the von Au family is appreciated.